1. Field of the Invention
This invention relates to the manufacture of soft, non-woven fabrics, especially such fabrics which do not contain binding agents. More especially, this invention is directed to an inexpensive process for providing soft, non-woven fabrics free of binding agents, which fabrics do not have a papery feel. This invention is directed to the fabrics themselves and to the process for their manufacture.
2. Discussion of Prior Art
Non-woven fabrics are sheet materials made of fibers in which the fibers are, in one way or another, bonded together at their intersections or crossing points. In this manner, the initially loose, fibrous material, e.g., cotton batting-like mat receives an appreciable strengthening. The time-honored method for securing the fibers together at their crossing points involves the impregnation of a loose, fibrous mat with a latex. The so impregnated mat is thereafter dried, which allows the latex to gather mainly at the intersections of the fibers. A membrane-like adhesive bond then forms, such as the one depicted in FIG. 4 of U.S. Pat. No. 2,719,802.
Adhesive-free, so-called thermoplastic bonds have been provided in non-woven fabrics. Details of the process by which the bonds are provided can be obtained from "Non-Woven Fabrics," page 31, chapter h, "Thermoplastic Fiber Bonding." In this process, thermoplastic fibers are admixed with the starting fiber mat. This mat is then passed between a pair of hot metal rolls having smooth surfaces. The heat from the rolls softens the thermoplastic fibers and thus they bond other thermoplastic fibers, or even non-thermoplastic fibers to one another. At the intersections or crossing points of the fibers a welding takes place which can be compared with the welding produced when two red-hot wires are welded together. After cooling, the fibrous sheet metarial has a considerable stability. However, it feels much like paper.
It has long been desired to provide an especially soft, thermoplastic, welded, non-woven fabric, especially one which did not have the feel of paper. It has therefore been desirable to provide a process for producing the same.